This blog provides updated forecasts and comments on current weather or other topics

Tuesday, November 16, 2010

Windstorm Factoids

Wednesday morning update: looks certain we will get major cold in western WA Monday-Wed next week and a real chance for light snow in the lowlands from Seattle south on Monday. And snow over the weekend on the N. Olympic Peninsula...more tonight!

We had quite a blow last night, although for most it wasn't more than the kind of windstorms we get a few times a winter. However, as I will mention to below, there were some subtleties here....for example, as I will explain there really was two distinct wind events going on. Also, later in the season there would have been far less damage and power outages. This was the first storm of the season and there was plenty of decayed and vulnerable branches ready to to...and the leaves still on many trees makes it worse! And there were plenty of careful construction folks who did not prepare for strong winds or forgot to finish their work (like a portion of the new departmental bicycle shelter that blew away!)

200,000 lost power last night and there were some impressive wind reports:

As I describe in my book, one of the most entertaining aspects of this and other windstorms is the firework show that occurs when the winds start blowing. Lightning? Nope. The multicolor displays are caused by transformer fuses or cutouts (see picture) When a circuit get grounded by a branch or some other object, these fuses can blow--cutting off the circuit with a bright flash. Then the associated neighborhood goes dark.Want to watch a video of the fun? Check this out:

1. A surge of strong westerly winds in the Strait as the low center moved by and the winds aloft aligned with the Strait. I call this a westerly Strait surge and they can get much stronger than Monday's event. One took out Ivar's Mukilteo Landing Restaurant in 2003.

2. Strong southerly and southwesterly winds in the southern to central Sound. This had associated with two things...the strong low passing to the north and strong lee troughing off the Olympics (more on this in another blog)

3. Very strong NW wind aloft associated with the passing low and its associated upper trough. This provided the strong winds at mountain stations.

Our high resolution models did get most of this right. To prove to doubters--here is the wind forecast (sustained winds) for 10 PM on Monday made more than 36 hr before (multiply by 1.5 to get gusts).

What about snow?

First, there will be heavy snow in the mountains. Feet of it. Be prepared if you are driving over it...you may need chains.

Over the lowlands, the big threat over the weekend will be NW Washington and the northern parts of the Olympic Peninsula. The latest runs will bring cool, air from the BC interior through the Fraser and other gaps in the Cascades...starting later on Friday. Vancouver, Blaine, the San Juans,Vancouver Is., and northern Olympics could get some snow very late Friday into the weekend. Serves those smug folks in the Sequimrainshadow right!...this time they will be on the windward side as strong NE wind head right towards them.

10 comments:

The eastern Palouse (Pullman-Moscow-Clarkston-Lewiston) also had a big blow last night (11/15-16). KPUW (Moscow-Pullman airport) recorded gusts up to 85 mph and KLWS (Lewiston Airport) reported gusts up to 64 mph. The latter is apparently an all-time November record (KPUW winds weren't noted by NWS for some reason). We had significant tree damage and power outages here in Moscow and other areas were similar. US 95 north of Moscow was apparently closed in places for much of the day due to down trees. It was a wild one for sure! We also had at least one thunder storm pass through.

In Eatonville we had gusts to 50 the other night. Right now....Wednesday, November 17 @ 7:52 AM.... winds from the SE are sustained 20-25 and gusting to 46.... I thought the strong winds for the day weren't supposed to materialize until later this afternoon and they were supposed to be from the SW.... ???

The picture you show in both your book and on your blog is one of what's called a cutout... Those are generally used to protect transformers and smaller side circuits when too much current flows through them (i.e. when something grounds the wires or causes the phases to touch one another).

But there is other equipment involved as well... including something called a recloser. A recloser is usually at the substation, and protects the main circuits. A recloser is what causes your lights to go out for a few seconds, then come back. It cuts the circuit for a brief period to allow the source of the power surge to get away from the lines (i.e. a fallen branch), then attempts to re-energize the circuit. If that's unsuccessful, then usually your power goes out and stays out.

If a cutout interrupts the power, it's one-shot deal. If there's enough current in the line to blow the cutout, your power stays out.

I do want to note one thing here: In neither of the videos below is there a transformer. Transformers rarely fail... most of the time, the colored flash you see is an arc on a wire or between two wires. There are lots of great examples on YouTube.

Example (from Bellingham) of an arc, which is what causes the fire. (This would've been one heck of a show at night!) Also note, toward the end you can see the effects of recloser in action - at 4:03 the power cuts, at 4:13 it reconnects, and at 4:18 it cuts again (beware, some foul language from people watching):http://www.youtube.com/watch?v=kVXi_0H_ZzM

Example of a cutout in action (in Australia, but same concept):http://www.youtube.com/watch?v=ATEWXsMawMg&feature=fvw

There is a book called Electrical Essentials for Powerline Workers that goes into great detail on this if you're interested in learning more.

Not only did the models underestimate the severity of Monday's winds, and it was fun to watch all the TV forecasters trying to explain why they all go it wrong, but then yesterday they were all saying that last night's storm wouldn't be as bad. Oh, yeah? Check out the Whidbey NAS readings -- consistent gusts above 50 from 5:56 to 8:56, and a gust of 60 at 7:56. Considerably higher than Monday's storm.

Oh, yes, and at 7:13 this morning the NWS finally issued a wind advisory for the NW interior. It warned of "WINDS: SOUTH TO SOUTHEAST WIND 25 TO 35 MPH WITH GUSTS TO 45 MPH." This over an hour _after_ Whidbey had recorded a gust of 53. Huh?

I realize that weather forecasting is not perfect, but missing two consecutive storms this badly in just two days suggests that some more work needs to be done on the models! And maybe advisories shouldn't warn of winds that are less than those actually happening.

I still love your blog, Cliff. You're one of the few people who's willing to explain not only what went wrong with the forecasts, but why. Now I'm waiting for you to explain why this storm also wound up much more severe than we were told it would be, at least up here in the islands.

I stand by my reasoning that the wind event on the 15th was remarkable...I'm an avid wind-watcher like everyone else reading these blogs ;) and am attending the UW for Atmospheric Sciences so I consider myself a little bank of windstorm history since around 1994 when I started staying up entire nights to predict and watch these wind events affect the green belt behind my house. After witnessing all those storms (1999, 2006. etc.) I'm positive, WITHOUT A DOUBT, that what I saw on the 15th between 8-12AM was one of a kind...never before have I seen or heard anything as ferocious (I've been in 80+mph winds on Bellingham bay as measured by my Kestrel 1000) and the damage to the greenbelt behind my house was SUBSTANTIAL, it brought down a massive number of trees AND some were perfectly living Big Leaf Maples and Red Alders...oh and a few massive Black Cottonwoods, but those are like toothpicks. I really think, Cliff that had you, Scott, Wolf Read or any other windstorm fanatic had been in Federal Way for this blow, you'd be talking about it for years. Also, I'm not one oft given to sensationalist claims about the weather but I have to make an exception for this and get the word out. Okay blablabla, I'm done :D now here's to hoping the GFS' Monday snowcast verifies *crosses fingers*

I live in the Redmond/Woodinville area and my school district has informed us that alternate bus routes may be used next week. Will enough moisture exist for snow in that area? I am thinking with highs in the mid-30s the thaw and refreeze cycle would make the roadways worse that just snow. Could you cover this in your next post?

I'm curious about what you have to say tonight. The 12Z surface temperatures on the WRF-GFS show high temperatures in the upper 30s to near 40 Monday-Wednesday with lows in the upper 20s to lower 30s. That doesn't seem like major cold to me, so I'm anxious to read your thoughts on it.